Insomnia is a form of dysomnia. Symptoms are described as light sleep, restless and unrefreshing. Insomnia can last from a few days or in some cases years.

Fatal Familar Insomnia, is a type of insomnia where the indiviual is unable to fall asleep at all, it's a rare inhertied dieases which progessively worsens. It's likely that offspring will have a 50% chance of developing the dieases.

Restless Leg Syndome can also cause insomnia. The uncomfortable sensation and the need to move one's leg, making it difficult for them to fall asleep.

Jet Lag, a person travelling through different itme zones and having to adjust their boy clock to sync with the country which they are in, can take sometime days. (east-west, west-east). The person's out of sync body clock will affect their eating sleeping and hormone regulation patterns.

Shift work, is also a circadian rhythm sleep disorder, which can cause insomnia.